As described in Patent literatures 1 to 3, converging mirror furnaces are known as systems used for manufacturing single crystal that converge infrared light onto, and thereby heat, the target aluminum oxide or other sintered compact body and seed crystal.
These converging mirror furnaces each comprise: a vertically moving stage on which aluminum oxide or other sintered body and seed crystal are set; a reflecting mirror constituted by a revolving ellipsoid and positioned in a manner surrounding the seed crystal in the horizontal direction; and a halogen lamp or other light source installed at one focal point of the revolving ellipsoid, with the sintered body and seed crystal positioned at the other focal point of the revolving ellipsoid.
Then, infrared light emitted from the light source is converged directly or via the reflecting surface of the reflecting mirror in such a way that it focuses onto, and thereby heats, the sintered body and seed crystal, and when this furnace is heating, the stage is lowered to grow single crystal.
Also, as described in Patent Literature 4, an art is known whereby a target base is placed at one focal point of a reflecting surface whose interior surface constitutes a revolving ellipsoid, and then infrared light is emitted from a surface light source being a heater installed in the reflecting surface, in order to heat the target on the target base with the infrared light directly or by causing it to reflect upon the ellipsoid.
Furthermore, as described in Patent Literature 5, a resistance furnace is known, which is a furnace used for semiconductor manufacturing in order to heat through the quartz board a silicon wafer placed on a quartz board. Even though infrared light is used as the heat source, however, the interior size of the furnace must be large enough to be able to heat the wafer or other object of a larger size by taking into account the quartz board inserted into the furnace and therefore it takes a long time for the temperature to rise enough to accomplish resistance heating, which makes it impracticable to achieve a single heating process that can be operated over a short period of time.
Additionally, a heat treatment system is also known, which comprises a surface constituted by multiple infrared lamps installed in a manner facing the surface of the placed wafer and positioned vertically above the wafer, and this surface is provided in parallel with the wafer surface, so that when this system is used to heat the wafer surface, infrared light is irradiated over an area large enough to cover the diameter of the wafer.